Liquid detergent compositions in emulsion form have been employed as all-purpose detergents for cleaning hard surfaces, such as, painted woodwork, bathtubs, sinks, tile floors, tiled walls, linoleum, paneling and washable wallpaper. Taking advantage of the mechanism of soil removal by emulsification, microemulsions were developed as a more efficient method of removing lipophilic/materials from substrates. These microemulsions include a lipophile, a surfactant, a cosurfactant and water. They are a thermodynamically stable phase in which the micelies have a particle size of less than 100 nm (nanometers), are transparent with no Tyndall scattering and do not separate over long periods of time. Microemulsions can solubilize oil without the use of expensive hydrotropes or vigorous mixing. They show very low interfacial tensions with oil and so will spread on soil surfaces aiding cleaning.
Microemulsions have certain disadvantages which make their application to practical problems difficult and often unpredictable. For example, in order to apply this technology to a particular problem, it is necessary to determine the ternary phase diagram for said system. In addition careful consideration must be taken of the surfactant and cosurfactant to be used. Microemulsions are sensitive to electrolytes and the phase behavior of each system must be well understood when diluting it. They are sensitive to oil chain length and foaming at high concentrations of surfactant.
M. Loth et al in U.S. Pat. Nos. 5,075,026 and 5,082,584 disclosed an improvement in microemulsion compositions containing an anionic detergent, a cosurfactant, a hydrocarbon and water comprising the use of a water-insoluble odoriferous perfume as the essential hydrocarbon ingredient. The cosurfactants of this reference have substantially no ability to dissolve oily or greasy soil and are selected from the group consisting of, among other entities, water-soluble alkanols have 3 to 4 carbon atoms, polypropylene glycol ethers, and monoalkyl ethers and esters of ethylene glycol or propylene glycol having 1 to 4 carbon atoms.
M. Loth et al in U.S. Pat. No. 5,076,954 delineated a concentrated stable, microemulsion, cleaning composition comprising synthetic organic detergent, cosurfactant, water and water-insoluble perfume as an essential hydrocarbon ingredient in an amount sufficient to form a dilute oil-in water (o/w) microemulsion composition. The cosurfactants of this reference are selected from the group consisting of, among other compounds, water soluble alkanols, of 2 to 4 carbon atoms, polypropylene glycol of 2 to 18 propoxy units, a monoalkyl ether of a lower glycol of the formula RO(X).sub.n H wherein R is C.sub.1-4 alkyl and X is CH.sub.2 CH.sub.2 O, CH(CH.sub.3)CH.sub.2 O or CH.sub.2 CH.sub.2 CH.sub.2 O and n is from 1 to 4.
P. J. Durbut et al in U.S. Pat. No. 5,035,826 described a liquid detergent composition which in liquid crystal form comprises one or more nonionic detergents with lesser amounts of anionic or cationic surfactants, a cosurfactant, such as tripropylene glycol butyl ether, a solvent for the soil, such as, an isoparaffin (9-11 carbons) or methyl cocoate and water as the major component.
M. Loth et al in U.S. Pat. No. 5,108,643 described an aqueous microemulsion comprising an anionic and/or nonionic synthetic organic detergent, water-insoluble perfume, water and cosurfactant where the cosurfactant adjusts interfacial conformation to reduce interfacial tension between dispersed and continuous phases of said detergents, perfume and water and therefore produces a stable microemulsion. This composition does not contain any solvents for oils and greases other than the perfume.
M. Kahlweit reviewed the state of the art in the field of microemulsions in Science, Volume 240, pages 617-621, April (1988).
It is an object of this invention to provide microemulsion cleaning formulations which show higher degrees of oil uptake and superior cleaning performance when compared with systems representative of the prior art.
It is another object of this invention to provide microemulsion cleaning formulations which are effective with smaller amounts of active ingredients reducing the amounts of residues left after cleaning over that obtained using prior art systems.
Other objects will become apparent to those skilled in the art upon a further reading of the specification.